Has anybody tried unsupervised deep learning from youtube videos?
Yes, it is possible, and yes, it probably has been done before. Odds are, however, the person(s) who tried were disappointed with the results and forgot to tell others. 

The reasons they might be disappointed could be any of the following:


Took to long to train
Even when fully trained, (or appeared to be), it did not give the expected output
Too sensitive to variations in the input